1. Field of the Invention
The present invention relates to an in-finder indicator and more particularly to an in-finder indicator capable of providing a superimposed indication in a finder of a single-lens reflex camera.
2. Description of the Related Art
In the field of cameras for taking photographs, AF cameras equipped with auto-focusing mechanisms (hereinafter referred to as “AF mechanisms”) have hitherto been used widely.
As an indicator incorporated in a finder of such a camera equipped with the AF mechanism, an in-finder indicator capable of presenting the so-called superimposed indication has been practiced, which includes a plurality of telemetric frames (AF frames) and indicates a selected one of the plurality of telemetric frames in superimposed relation to a subject image (also called a “finder image”) in a finder viewing frame.
In one example of the known in-finder indicator capable of presenting the so-called superimposed indication, a desired indication position is defined as a “position of one of the plurality of telemetric frames which is a target of the auto-focusing operation”. Then, an “in-focus state” or an “out-of-focus state” is represented by switching over the indication mode of that position, and that position is displayed in superimposed relation to the finder image. Such superimposed indication enables a user of the camera to highly intuitively understand the meaning of the presented indication and to easily perform the photographing operation of the camera.
An indication device of the in-finder indicator employs, e.g., a luminous illumination member, such as a light emitting diode (LED), to switch over to one of a turned-on state and a turned-off state so that an indication state or a non-indication state is represented selectively. That in-finder indicator presenting the illumination-type superimposed indication is advantageous in that, because of high viewability in the turned-on state, the user is less likely to miss the presented display state. Another advantage is that various display colors can be selectively used by preparing a plurality of illumination light sources, and the luminous indications in different colors ensure very high viewability in presenting the indications even when the luminance of the subject is low and the area within a finder viewing frame is dark.
For a camera equipped with the above-described known in-finder indicator capable of presenting the superimposed indication, there has hitherto been proposed an in-finder indicator capable of presenting the illumination-type superimposed indication in which, for example, an indicating zone made of a group of many minute prisms is formed on an indication member that is made of a reflecting plate disposed adjacent to a focusing screen in the camera. When an illumination beam from an illumination device is obliquely emitted toward the indicating zone, only the light reflected from the minute prisms is allowed to enter a finder optical system so that the user is able to view the indicating zone with the finder.
That type of in-finder indicator comprises the indication member actually viewable with the finder, and the illumination device for emitting the illumination beam toward the indication member. Assuming here the case where such an in-finder indicator is applied to, for example, a camera equipped with a multipoint telemeter having a plurality of telemetric points, the in-finder indicator is used to indicate telemetric frames.
In the multipoint telemeter, a plurality of telemetric locations are scattered over a wide area within a finder viewing frame, and the telemetric frame corresponding to the indicating zone is set for each of the telemetric locations. The illumination device adapted for the multipoint telemeter is required to be able to selectively illuminate predetermined locations scattered over a wide area of the indication member, i.e., the locations of the plurality of telemetric frames.
Further, various types of in-finder indicators other than the above-described one have hitherto been proposed as disclosed in, e.g., Japanese Patent No. 3272871 and Japanese Unexamined Patent Application Publication No. 2002-268128.
An in-finder indicator disclosed in, e.g., Japanese Patent No. 3272871 is adapted for use in a single-lens reflex camera equipped with a finder unit comprising a penta prism, etc. In this in-finder indicator, as shown in FIG. 8, illumination members for presenting the superimposed indication (such as a light emitting devices 118 and a light projecting lens 119 for projecting a beam of light emitted from each light emitting device in a predetermined direction) are disposed in a space above a penta prism 112 of the finder unit, and the illumination beams from the illumination members are introduced to enter the interior of the penta prism 112 from a predetermined surface 112a (inclined surface obliquely facing the upper left side in FIG. 8). Note that FIG. 8 is a schematic sectional view showing a layout of principal parts of the disclosed in-finder indicator, which are disposed inside the camera.
In the disclosed in-finder indicator thus constructed, the illumination beam emitted from the light emitting device 118 enters the light projecting lens 119 where an optical path A is bent in a predetermined direction such that the light beam enters the predetermined surface 112a of the penta prism 112. Then, the light beam passes the interior of the penta prism 112 and exits from another predetermined surface 112b. Thereafter, the light beam passes through a condenser lens 115 and reaches a predetermined one of a plurality of indicating zones (telemetric frames) on an indication member 113, thereby to illuminate it.
Thus, with efficient layout of the light emitting devices inside the camera, a more compact camera can be realized even when the plurality of indicating zones are set over a wide area within a photographing frame.
An in-finder indicator disclosed in Japanese Unexamined Patent Application Publication No. 2002-268128 is adapted for use in a single-lens reflex camera equipped with a finder unit comprising, instead of the glass-made penta prism, a hollow penta mirror, etc. Illumination members are disposed at an upper part of an opening of the penta mirror at a position closer to an eyepiece optical system, and beams of light emitted from light emitting devices of the illumination members are introduced to pass the interior of the penta mirror, thereby illuminating indications on an indication member disposed at a lower part of the penta mirror.
With that arrangement, since the hollow penta mirror is used instead of the glass-made penta prism and the illumination members are disposed at the opening part of the penta mirror, an in-finder indicator can be constructed in a simplified structure with efficient use of a space. As a result, a more compact camera can be realized.
Meanwhile, single-lens reflex cameras equipped with pop-up built-in strobe units have been widely practiced in recent years. In such a camera, the pop-up built-in strobe unit is usually disposed at the upper part of a penta prism in the vicinity thereof.